Vehicle lamp



March 8, 1927.;

1,620,202 A. GRAVE I VEHICLE LAMP Filed July 19 1% L Patented Mu. s',1927.

1,520,202 UNITED STATES PATENT? .orr cs.

mom) Gnu-Es, or. FBmroN-oN-sm, imam.)

vnnrcma y mu filed m 19; 1 22, Serial No. 576,996, and in Great Britainm 29. 1921.

This invention relates to lamps fitted with "reflectors and used forohead and side lights and in vehicles, of the type in which the l ghtsource in combination with a small hemispherical mirror is placed insidea parabolic or similar reflector, part of the light from the sourcefalling directly on to the reflector part on to the mirror whence it isreflected on to the-reflector. In this t e one half only of the hollowsurface of t e reflector is used and the otherhalf is commonly supressed.

,One'o the ob'ects of the invention is to overcome the di culti foundwith reflectors commercially obtaina le', that the optimum o si tion isnot always at the geometrical ocus as 1t would be in the case of aperfect a mirror.

Another object of theinvention is to suppress rays above the horizontaland to cast the li ht in a low flat topped beam and 'so ,abolis glare,and further to make the beam as uniform as 'ossible.

A further 0 ject is to enable the user of- 3151 lamp to vary the natureof the beam at Tb attain the first object, the invention consists inmounting the source of light Swhich may be thefilament of anincanescentelectric lamp) together with the small hemis herical mirror (which maybe formed by silvering one half of the spherical bulb of the lamp) onthe holder which is capable of movement in all three dimensions, so thatthe source of light together with the mirror may be brought to theoptimum position in the reflector and there fixed. e

To attain the second object of the invention, the light sourceispositioned relatively to the reflector so that it is situated not at thefocus or'optimum position of the reflector but in advance or in rearthereof accord ing to whether the lamp is-one in which the upper half ofthe reflector is being used or w ether it is one employing the lowerhalf of, the reflectoryand .to make the beam uniform it is furtherpreferred to positionthe light source relatively to the hemisphericalmirror so. that it is not at the centre of curvature thereof butslightly in front or in rear of the centre of curvature and inthe sameplane. I To attain the third object, the invention consists in somounting the light source and lamp bodily, either of the'filaments mayat. will be switched on. One of these filaments is placed at thefocus oroptimum position of the reflector, and the other is so situated inrelation to the first that it isfin advance or in rear of the optimumposition according as the upper or lower half of the reflec tor-is used.

In the accompanying drawings which illustrate the manner in which theseobjects are accomplished Figure 1 is a diagram'illustrating one way ofcarrying the invention intoefiect in connection with an upper reflector.

Figure 2 is a view similar to Figure 1 but show ng an embodiment using alower reflector.

Figure 3 is a view illustrating the embodiment of the invention in a comlete unit.

- .Fi 're 4; is a detail view furt er illustrating the adjusting meansfor the lamp.

Figure .1 shows a parabolic reflector A g whose-axis is represented bythe line X- X and the focus isat F. M isa small semicircular mirrorwhose centre of curvature is at C. 'L and L are sources oflight, theformer of which is. situated in advance of the. focus F of the reflectorin the same plane{ as the centre of curvature C of the mirror M butslightly in rear of it. 'The mirrow will produce an image L of L on theother side of the centre of curvaturei Ignorin for a moment the fefl'ectof the image at the light from L as reflected byA will produce aconverging beam which after coming to -a focus will again diverge togive a beam in front of the lam and below the horizontal axis XX and tis beam will have a semicircular section with a flatjtop consisting of aconcentric series of semifannuli with dark interspaces. The position ofL may beso adjusted relatively to M that the image L will cast a similarbeam whose semi-annuli will be coincident with the dark inte aces of thebeam-cast by L. The result-o this will be a nearly homogeneous beam ofsemi% circular section with a flat top below the horizontal and freefrom glare but well in front of hemispherical mirror M inasmuch as thisarrangement renders the beam more uniform but if desired the lightsource L may be placed at the centre of curvature of the hemisphericalmirror M and in such case the beam will befree from the glare eflectrovided of course that the other important feature be presented, that isto say, that the light source L shall not be at the focus F of thereflector.

As previously indicated in Figure 1 the filament L is coincidentwith'the focus or optimum position F of the reflector A, and when it isrendered incandescent the concentrated beam is obtained. Therelationship of the filament L and its image L is as previouslydescribed, and when a flattopped anti-dazzle beam is required, thefilament L is extinguished and L rendered 1ncandescent. 1

Figure 2 is similar to Figure 1, but in this case the lower half of thereflector is used. Figures 3 and 4: illustrate a practical method ofcarrying-the invention-into effect. An outer shell 1 together with abase 2 is mounted on a rigid frame 4 provided with lugs 3 by means ofwhich it may be attached in any desired position. Within this rigidframe 4 is mounted a frame 5 carrying a parabolic reflector 6. The frame5 is capable .of slight movement about pivots 7 under the influence ofthe screw and spring ad'ustment 8 by means of which it maybe tllted ifdesired. The lamp 9 has its lower portion 10 silvered and is mounted ona cylindrical spindle 10 lar 10 mounted 'on the centre of a. washer 18.This washer 18 is held .between' two rings 17 and 1'2 the latterprojecting through the-plate 13. The apertures of the rings 17, 17, andthe plate 13 are of greater diameter than the spindle. If the screws 19be loosened the spindle may be moved in any direction radial to the axisof the reflector and may befixed in the optimum position by tighteningup the screws 19. Longitudinal movement of the lamp may then be effectedby loosening the milled head on the split collar 10 and tightening upagain when the lamp has received sufficient axial.

movement to bring the source of light-in advance of the focus of thereflector. The adjustment of the beam may be effected by placing thelamp so as to cast a beam on to a vertical wall about 10 feet away andmoving the bulbuntil the berm is as bright as possible, this will occurwhen the filament 1s in the optimum point of the reflector. The lamp isthen moved axially forwards until the beam assumes a flat topsemi-cirhead screwed tight. T

which passes through a split 001- cular shape without glare andthemilled e plate 13 is mounted on a spindle 14; passing through a I fixedblock 15 and is capable of being pulled backwards by the Bowden wire 12against the action of a sprin 16 so that at will the driver may alter te character of the beam.

It is obvious that in the'case of an existing/ lamp having a parabolicor similar reflector,

such lamp might be converted to work in accordance with the invention byfixedly adapting to the reflector an attachable fitment carrying movablymounted therein a source of light, and a small hemispherical mirror, thesource of li ht and the mirror being in fixed relations but capable ofadjustment in the fitment as previously described relativel to the reector A in three directions, so t at the source 0 light is capable ofbeing brought to the focus or optimum position of the reflector and thenwithdrawn therefrom to another axial position by movement in the adapterfitment.

Claims:

1. A lamp of the class described including an outer shell, a main framewithin said shell, a reflector carrying frame pivotally mountedinsaidmain frame, screw means for adjusting the reflector carrying framewith reference to themain'frame, a lamp carrying unit including a platehaving a spindle, a fixed block on the main receiving the spindle, aspring confined between the spindle and the block, a flexible connectionfor said spindle whereby the same may be shifted in the block to movethe lamp carrier axially of the reflector,

frame for.

the axis of the reflector.

2. In a lamp, the combination of a frame,

a carrier guided on the frame for rectilinear movement thereupon betweentwo limiting positions, a reflector, means for' mounting the reflectoron the frame, said means having an adjustment for bringing the axis 'ofthe reflector into parallelism with the path of movement of the carrier,an electric light, means for mounting the lamp upon the carrier, saidmeans having adjustment for bringing the filament of the light into thefocus of the reflector when the carrier is in one limiting osition, andoperator controlled means or shifting the carrier from one limitingposition to the other with respect to the frame to chan e the characterof the beam emitted by tfie-lamp while the lamp is in use.

3. In a lamp, the combination of a frame, a carrier guided on the framefor rectilinear movement thereupon between two limiting positions, areflector, means for mounting the reflector on the frame, said meanshaving an adjustment for bringing the axis of the reflector intoparallelism with the path of movement of the carrier, anelectric light,

means for mountin the lamp upon the carlamp is in use, a secondreflector within the 10 rier, said means aving adjustment for -firstreflector, the focal point of the first re bringin the filament (i thelight into the flector, the lamp and the second reflector focus 0 thereflector when the carrier is in, coinciding when the carriage is in thelimitone limiting osition, and operator com ing position for securing aconcentrated trolled means or shifting the carrier from beam. 15 onelimiting position to the other with In testimony whereof I have affixedmy respect to the rame to change the character signature hereto this30th dagof June, 1922. of the beam emitted bythe lamp while the ARNOLGRAVES.

